In-situ heating/cooling neutron diffraction experiments were performed on a γ-TiAl based alloy doped with Mo and/or C. The structural analysis was complemented by differential scanning calorimetry and electron microscopy. Description of high temperature α phase with new model of partially disordered View the MathML sourceα2′-Ti3Al phase instead of a fully disordered α-Ti is proposed. The atomic redistribution in the γ phase is related to a wide α-transus signal on the DSC curves. Sections of temperature phase stability diagrams constructed from diffraction data for heating and cooling are presented.